Network connectivity allows your computer to communicate with other hosts on your network and the Internet. Connectivity might be full (Internet and intranet), partial (local subnet only), or non-existent. The core is unable to perform any transfers.
TCP/IP failed to establish an outgoing connection because the selected local endpoint was recently used to connect to the same remote endpoint. This error typically occurs when outgoing connections are opened and closed at a high rate, causing all available local ports to be used and forcing TCP/IP to reuse a local port for an outgoing connection. To minimize the risk of data corruption, the TCP/IP standard requires a minimum time period to elapse between successive connections from a given local endpoint to a given remote endpoint.
Any unused iSCSI connections are exhausting the ephemeral ports due to a failing port on an iSCSI switch. The issue appeared in Microsoft patches released April 2017.
Running "netstat -aqo" responds with a large amount of BOUND ports by PID 4 (System) thus exhausting ephemeral TCP ports. Further investigation reveals several attempts per second attempting to connect to port 3260.